肽类树状大分子及其生物医学应用

肽类树状大分子是近年来发展起来的一类新型生物医用高分子材料,它除了具有普通树枝状分子的特征如规整性、高度支化、表面呈现高密度功能团、尺度为纳米级、单一分子量等之外,同时还具有类似蛋白一样的球状结构、优良的生物相容性、水溶性、耐蛋白酶水解、生物降解等独特的性能。肽类树状大分子的上述特点,使它在生物医学应用中显示出诱人的前景。系统论述了肽类树状大分子的合成方法、以及在疾病诊断与治疗等生物医学领域中的应用。如作为MRI(磁共振成像)分子探针、诊断试剂以及基因治疗试剂等。将造影官能团偶联到肽类树枝状分子上,即得肽类树枝状MRI分子探针,该类MRI分子探针具有优良的生物相容性,纳米级尺寸结构。含氨基的肽类树枝状分子与基因(DNA)复合成纳米尺寸的粒子,可有效进入细胞,将DNA转移到目标部位,达到基因转染的目的。     

一维氧化镓纳米材料研究进展

随着纳米材料制备技术和性能研究的发展,一维纳米材料日益受到人们的关注.简要介绍了一维氧化镓纳米材料的制备方法及其光致发光机理,并指出了当前研究过程中存在的问题和可能的发展方向.     

溶液中镓的提取与分离研究进展

从钢铁、有色金属、煤化工及磷化工等行业中的含镓物料中回收镓,需面临从含有多种金属离子的溶液中分离镓的问题。综述了含镓溶液中提取和分离镓的研究现状,分析和讨论了溶剂萃取、液膜萃取、萃淋树脂萃取等工艺的关键影响因素,并展望了研究趋势。溶剂萃取、液膜萃取及萃淋树脂萃取工艺皆能有效提取和分离溶液中的镓,其中协同萃取、液膜萃取及萃淋树脂萃取的选择性和萃取效率高,而且流程短、环境友好,应用前景好,是今后研究的发展方向。     

Dependence of Electron Density on Fermi Energy in N-Type Gallium Antimonide

The majority electron density as a function of the Fermi energy is calculated in zinc blende, n-type GaSb for donor densities between 10¹⁶ cm⁻³ and 10¹⁹ cm⁻³. These calculations solve the charge neutrality equation self-consistently for a four-band model (three conduction sub-bands at Γ, L, and X and one equivalent valence band at Γ) of GaSb. Our calculations assume parabolic densities of states and thus do not treat the density-of-states modifications due to high concentrations of dopants, many body effects, and non-parabolicity of the bands. Even with these assumptions, the results are important for interpreting optical measurements such as Raman measurements that are proposed as a nondestructive method for wafer acceptance tests.     

我国伴生稀散金属锗镓的选矿回收研究概况

概述了稀散金属元素锗、镓的特点和我国选矿回收存在的问题,以及我国选矿回收锗、镓的主要企业的研究概况,指出了目前选矿过程存在的主要问题和下一步的重点研究方向。     

Ni对RPV模拟钢中富Cu原子团簇析出的影响

用原子探针层析技术和时效模拟方法,研究了不同N i含量并且提高了Cu含量的反应堆压力容器(RPV)用模拟钢中富Cu、富N i和富Mn原子团簇的形成。结果表明,提高钢中的N i含量会促使富Cu原子团簇的析出,富Cu原子团簇中含有N i和Mn。实验检测到富N i的原子团簇,团簇中含有Cu和Mn,富N i原子团簇可以作为富Cu原子团簇析出时的形核区。实验还检测到富Mn原子团簇,当Mn原子团簇中含有较高的N i时,它也可以成为富Cu原子团簇析出时成核的地方。由于钢中的合金元素N i在形成富N i原子团簇后会成为富Cu原子团簇析出时成核区,因而提高N i的含量将促进富Cu原子团簇的析出,这是合金元素N i会增加压力容器钢中子辐照脆化敏感性的本质原因。     

Thermal Effects on the Crystallization Kinetics,and Interfacial Adhesion of Single-Crystal Phase-Change Gallium

Although substrates play an important role upon crystallization of supercooled liquids, the influences of surface temperature and thermal property have remained elusive. Here, the crystallization of supercooled phase-change gallium (Ga) on substrates with different thermal conductivity is studied. The effect of interfacial temperature on the crystallization kinetics, which dictates thermo-mechanical stresses between the substrate and the crystallized Ga, is investigated. At an elevated surface temperature, close to the melting point of Ga, an extended single-crystal growth of Ga on dielectric substrates due to layering effect and annealing is realized without the application of external fields. Adhesive strength at the interfaces depends on the thermal conductivity and initial surface temperature of the substrates. This insight can be applicable to other liquid metals for industrial applications, and sheds more light on phase-change memory crystallization.     

External Knowledge and Innovation Performance in Clusters: Empirical Evidence from the Uruguay Software Cluster

The importance of geographic proximity for innovation has been widely stressed in the cluster literature. Yet, new insights from the inter-organisational network and cluster literatures underline the role of non-local linkages in enabling firms in networks to enhance learning and to innovate. This paper contributes to this literature by examining the importance of local and non-local knowledge networks for the innovation performance of firms in clusters. Our analysis is based on primary data from a survey of 95 software firms clustered in Montevideo, Uruguay. The results highlight that the most innovative firms in clusters heavily rely on non-local knowledge networks. Moreover, the number of indirect local ties to other firms is a better predictor of innovative performance than the number of direct local ties. Finally, our findings confirm the presence of knowledge gatekeepers in clusters and emphasise their role in enhancing innovation in clusters by absorbing knowledge from extra-cluster sources and diffusing it to other local firms.     

广东省产业群发展的实证研究与政策建议

文章首先用集群指数模型对广东省39个行业近10年的集群状况进行了测度，其次在测度的基础上对39个行业分三类进行了现状和趋势的描述与分析，最后提出了广东要实施产业集聚的引进外资新战略；加强产学研结合，积极引进跨国公司的研究开发机构；培养和造就新的工业文化和精神等结论和建议。     

Metal Clusters on Semiconductor Surfaces and Application in Catalysis with a Focus on Au and Ru

Metal clusters typically consist of two to a few hundred atoms and have unique properties that change with the type and number of atoms that form the cluster. Metal clusters can be generated with a precise number of atoms, and therefore have specific size, shape, and electronic structures. When metal clusters are deposited onto a substrate, their shape and electronic structure depend on the interaction with the substrate surface and thus depend on the properties of both the clusters and those of the substrate. Deposited metal clusters have discrete, individual electron energy levels that differ from the electron energy levels in the constituting individual atoms, isolated clusters, and the respective bulk material. The properties of clusters with a focus on Au and Ru, the methods to generate metal clusters, and the methods of deposition of clusters onto substrate surfaces are covered. The properties of cluster-modified surfaces are important for their application. The main application covered here is catalysis, and the methods for characterization of the cluster-modified surfaces are described.     

Thermal Conductivity Measurements of Liquid Mercury and Gallium by a Transient Hot-Wire Method in a Static Magnetic Field

The transient hot-wire method, incorporating a static magnetic field, has been developed to measure thermal conductivities of liquid mercury and gallium. Prior to the measurements, the effect of an alumina-coated hot wire on the measurements has been evaluated. Natural convection in the liquid metals has been effectively suppressed by the Lorentz force acting on the liquid metals in a static magnetic field. The thermal conductivities of liquid mercury and gallium have been determined to be 7.9 W.m ⁻¹.K ⁻¹ at 291 K and 24 W.m ⁻¹.K ⁻¹ at 302.9 K, respectively.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

纳米Au团簇在氧化钛修饰的介孔分子筛MCM-41中的组装

以钛酸丁酯为ＴｉＯ_２前驱体,使ＴｉＯ_２均匀分散于纯硅介孔分子筛ＭＣＭ－４１的介孔孔道内表面,利用ＴｉＯ_２光学性质将ＡｕＣｌ－４还原为Ａｕ（０）并组装于氧化钛修饰的ＭＣＭ－４１孔道中．对所合成的Ａｕ负载的氧化钛修饰的ＭＣＭ－４１进行了ＸＲＤ,ＸＰＳ,Ｎ_２吸附－脱附曲线,及固体ＵＶ－Ｖｉｓ漫反射等多种结构表征．由ＸＰＳ谱和固体ＵＶ－Ｖｉｓ漫反射吸收光谱的ｐｌａｓｍｏｎ吸收峰证明Ａｕ团簇呈现０价的金属状态．     

基于DEA-SBM/Malmquist的广东省创新型产业集群的创新效率研究

分析了创新型产业集群的特征,指出创新型产业集群中丰富的协同创新活动是促进企业创新绩效的有效方法,并提出创新平台是协同创新的优良载体,建设创新平台能有效促进企业创新。在实证分析中利用DEA SBM超效率模型和Malmquist指数,将创新平台加入到创新效率测度的投入变量中,以专利申请数为产出变量,对广东省不同地区的创新型产业集群的创新效率进行了测度。研究结果表明：广东省不同地区创新型产业集群之间的创新效率整体较高但是存在一定差异;创新平台作为创新投入变量是一个能深刻影响测量结果的因素;集群之间的创新平台建设差异较大,一些地区创新平台建设滞后。基于此提出5点政策建议。     

Innovation Clusters in Technological Systems: A Network Analysis of 15 OECD Countries for the Mid‐1990s

The paper aims to investigate how innovations cluster in different technological systems (TSs) when their “techno‐economic”, rather than “territorial” space, is considered. Innovation clusters of economic sectors are identified by referring to the innovation “potential” represented by their R&D expenditure and by applying social network analysis to the intersectoral R&D flows matrices of 15 OECD countries in the mid‐1990s. Different clusterization models are first tested in order to detect the way sectors group on the basis of the embodied R&D flows they exchange. Actual clusters are then mapped in the different TSs by looking for intersectoral relationships which can be qualified to constitute “reduced TSs” (ReTSs). In all the 15 TSs investigated the techno‐economic space appears organized in hierarchies, along which its constitutive sectors grouped into clusters with different density and composition. Once ReTSs are looked for, the 15 TSs display highly heterogeneous structures, but with some interesting similarity on the basis of which different clusters of TSs can be identified in turn.     

Metal nitride cluster fullerenes: their current state and future prospects

The world of endohedral fullerenes was significantly enlarged over the past seven years by the cluster fullerenes, which contain structures such as the M(2)C(2) carbides and the M(3)N nitrides. While the carbide clusters are generated under the standard arc-burning conditions according to stabilization conditions, the nitride cluster fullerenes (NCFs) are formed by varying the composition of the cooling gas atmosphere in the arc-burning process. The special conditions for NCF synthesis is described in detail and the optimum conditions for the production of NCFs as the main product in fullerene syntheses are given. A general review of all NCFs reported to date consists of the structures, properties, and stability of the NCFs as well as the abundance of the NCFs in the fullerene soot. It is shown that all cages with even carbon atoms from C(68) to C(98) are available as endohedral nitride cluster structures (with the exception of C(72), C(74), and C(76)). Specifically, the NCFs form the largest number of structures that violate the isolated pentagon rule (IPR). Finally some practical applications of these cluster fullerenes are illustrated and an outlook is given, taking the superior stability of these endohedral fullerenes into account.